Field of the Invention
Exemplary embodiments of the present invention relate to a blade control apparatus and method for a wind power generator, and a wind power generator using the same, and more particularly, to a blade control apparatus and method for a wind power generator, which measures the change in electrical characteristic of a member forming a blade so as to control the blade, and a wind power generator using the same.
Description of the Related Art
A wind power generator refers to a power generator which generates power using wind power which is natural energy. The wind power generator generates electricity by converting wind power into a mechanical rotational force, and includes a blade, a nacelle, and a tower.
The wind power generator generates a rotational force based on an aeromechanical lift force of the blade which acts against wind blowing from the front. The rotation of the blade changes the aerodynamic load distribution around the blade, and the change of the aerodynamic load distribution is applied as a bending load or twisting load to the blade.
The blade may be damaged by the application of such a load and the surrounding environment condition such as rainfall, corrosion caused by salt contained in seawater, or collision with foreign matters in the air. In this case, deformation, deterioration, or delamination may occur inside and outside the blade.
According to a conventional method, an operator checks the state of a blade with the naked eye, when a wind power generator is regularly inspected, or when the rotation of the blade is stopped. Then, the operator repairs the blade, changes the operation condition, or replaces a part in response to the state information of the blade, which is analyzed through the checking operation.
In such a method, however, the state of the blade can be checked only in a state where the blade is stopped, and the operator must check the state of the blade with the naked eye.
In order to solve such a problem, various techniques have been proposed to determine whether a blade for a wind power generator is damaged.
For example, a measurement unit such as an optical fiber sensor or strain gauge may be used to check the state of a blade, and the blade may be controlled according to the state of the blade.
As a specific example of an apparatus for detecting the state of a blade, Korean Patent Laid-open Publication No. 10-2013-0052965 has disclosed a physical quantity sensing apparatus of a wind turbine blade.
The disclosure relates to a physical quality sensing apparatus of a wind turbine blade, which includes optical fiber for totally reflecting light incident from a light source and a Bragg grating for sensing a physical quantity of a blade for wind power generation by reflecting light at a Bragg wavelength range in the light transmitted through the optical fiber.
The apparatus according to the above-described disclosure includes a required number of optical fiber Bragg grating sensors and temperature-compensated Bragg grating sensors which are attached at the top or bottom of a shear web, and senses the temperature, the strain rate, and the deflection of the blade through the sensors.
However, since the optical sensors or strain gauges are expensive and difficult to deal with, only a skilled engineer can install the optical sensors or strain gauges. Furthermore, since the optical sensors or strain gauges are vulnerable to vibration, the optical sensors or strain gauges may frequently break down after installation. Thus, there are difficulties in managing and repairing the optical sensors or strain gauges.
Furthermore, since the optical sensors or strain gauges are sensitive to temperature change, a process of removing a change caused by temperature effect using data processing technology must be accompanied. The process is technically difficult to perform, and requires a compensation process. Thus, it is difficult to secure the reliability of acquired information.
In particular, the measurement units can sense external deformation of the blade, such as deflection, but cannot sense internal damage. Therefore, the measurement units have limitation in availability.